From: Andi Kleen <andi@firstfloor.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Sheng Yang <sheng@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-mm <linux-mm@kvack.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86_64
Date: Thu, 14 May 2009 16:27:49 +0200 [thread overview]
Message-ID: <20090514142749.GE10933@one.firstfloor.org> (raw)
In-Reply-To: <4A0C27AA.4010006@zytor.com>
On Thu, May 14, 2009 at 07:16:10AM -0700, H. Peter Anvin wrote:
> Andi Kleen wrote:
> >>>
> >> The right way to do it is to pass the proper type of register.
> >
> > For the input index register you don't actually need 64bit and for the
> > value it's typically memory anyways.
> >
>
> If you have a 64-bit operation you have a 64-bit index register. And
> you need a 64-bit index for it to handle over 2^31 (since it is signed.)
Pretty much all the bit ops and a few other operations currently have
2/4GB limits on x86-64. I don't think that's going to change.
In the kernel nothing is ever that big continuously anyways.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Sheng Yang <sheng@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-mm <linux-mm@kvack.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86_64
Date: Thu, 14 May 2009 16:27:49 +0200 [thread overview]
Message-ID: <20090514142749.GE10933@one.firstfloor.org> (raw)
In-Reply-To: <4A0C27AA.4010006@zytor.com>
On Thu, May 14, 2009 at 07:16:10AM -0700, H. Peter Anvin wrote:
> Andi Kleen wrote:
> >>>
> >> The right way to do it is to pass the proper type of register.
> >
> > For the input index register you don't actually need 64bit and for the
> > value it's typically memory anyways.
> >
>
> If you have a 64-bit operation you have a 64-bit index register. And
> you need a 64-bit index for it to handle over 2^31 (since it is signed.)
Pretty much all the bit ops and a few other operations currently have
2/4GB limits on x86-64. I don't think that's going to change.
In the kernel nothing is ever that big continuously anyways.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
--
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next prev parent reply other threads:[~2009-05-14 14:22 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-13 8:17 [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86_64 Sheng Yang
2009-05-13 8:17 ` Sheng Yang
2009-05-13 8:38 ` Andi Kleen
2009-05-13 8:38 ` Andi Kleen
2009-05-14 3:45 ` Sheng Yang
2009-05-14 3:45 ` Sheng Yang
2009-05-14 8:32 ` Andi Kleen
2009-05-14 8:32 ` Andi Kleen
2009-05-14 14:09 ` H. Peter Anvin
2009-05-14 14:09 ` H. Peter Anvin
2009-05-14 14:16 ` Andi Kleen
2009-05-14 14:16 ` Andi Kleen
2009-05-14 14:16 ` H. Peter Anvin
2009-05-14 14:16 ` H. Peter Anvin
2009-05-14 14:27 ` Andi Kleen [this message]
2009-05-14 14:27 ` Andi Kleen
2009-05-14 14:25 ` H. Peter Anvin
2009-05-14 14:25 ` H. Peter Anvin
2009-05-14 14:33 ` Andi Kleen
2009-05-14 14:33 ` Andi Kleen
2009-05-14 14:36 ` H. Peter Anvin
2009-05-14 14:36 ` H. Peter Anvin
2009-05-13 16:18 ` H. Peter Anvin
2009-05-13 16:55 ` H. Peter Anvin
2009-05-13 16:55 ` H. Peter Anvin
2009-05-13 17:29 ` H. Peter Anvin
2009-05-14 3:52 ` Sheng Yang
2009-05-14 3:52 ` Sheng Yang
2009-05-14 14:09 ` H. Peter Anvin
2009-05-14 14:09 ` H. Peter Anvin
2009-05-14 13:57 ` Christoph Hellwig
2009-05-14 13:57 ` Christoph Hellwig
2009-05-14 14:29 ` H. Peter Anvin
2009-05-14 14:29 ` H. Peter Anvin
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